<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script src="https://cdn.bootcss.com/vue/2.5.18-beta.0/vue.js"></script>
    <style>
        .show{
            background: red;
        }
    </style>
</head>
<body>
    <div id="app">
        <p :class="{show:isShow}" @click="handleClick">hello world</p>
    </div>
    <script>
        var vm = new Vue({
            el:"#app",
            data:{
                isShow:false
            },
            methods:{
                handleClick(){
                    this.isShow = !this.isShow
                }
            }
        })
    </script>
</body>
</html>